In a steam generator of a nuclear plant, an in-channel-head operation device is used to carry out an operation inside a water chamber. Further, in recent years, there has been proposed an in-channel-head operation device that has a manipulator of which a front end portion is equipped with a working tool. Further, since a floor surface of the water chamber has a spherical shape, there has been proposed a configuration in which such an indoor operation device is installed while being suspended from a tube sheet surface of the water chamber in order to improve the workability of the in-channel-head operation device. As such an in-channel-head operation device, a technique disclosed in Patent Literature 1 is known.
Here, a plurality of heat transfer tubes are opened and arranged on the tube sheet surface of the water chamber. Therefore, in such an in-channel-head operation device, there has been proposed a configuration in which a clamper is provided so as to clamp and hold the heat transfer tube by inserting a front end portion thereof into the heat transfer tube and the in-channel-head operation device is fixed to the tube sheet surface by the clamper. As an in-channel-head operation device having such a clamper, a technique disclosed in Patent Literature 2 is known.